Nick Clegg insisted today that the Liberal Democrats remained committed to scrapping tuition fees, despite saying the flagship policy might have to be put on hold as part of the party's commitment to "bold" decisions on spending cuts.

"There is no question mark over the Liberal Democrats' commitment to scrapping tuition fees," Clegg told delegates at his party's annual conference in Bournemouth.

"The only question mark is when we can afford to scrap the tuition fees."

Sections of party got the jitters when he used a rally speech last night to warn that the need for "savage" public spending cuts might force him to ditch his party's promise to abolish tuition fees.

Clegg said last night the party needed to "realistic" about whether the flagship policy was affordable given the country's mountain of debt, a view repeated on The Andrew Marr show on BBC1 earlier today.

Pressed on whether the Lib Dems were ditching the policy, Clegg told Marr that the current economic situation meant no politician could "look you in the eye and say there isn't an issue about affordability of very big ticket public spending commitments".

"It's a fact we need to treat people like grown-ups and accept the debate has shifted," he added.

Pressed on whether this meant the Lib Dems were binning the idea, Clegg said the party was looking at where it could make big savings such as Trident and tax benefits to above average income families, "then see what money is spare".

His comments prompted former leader Charles Kennedy to warn of the dangers of ditching a totemic commitment so closely associated with the party.

Clegg's chief of staff, Danny Alexander, admitted: "People in the party are concerned about it."

But Clegg appeared to have fine tuned his message this afternoon as he told delegates there was "no question mark" over the Lib Dems' commitment to scrapping tuition fees, which would cost the exchequer an estimated £2.5bn.